OP if you PM me privately with where you are thinking of living I can tell you what your catchment school is. Definitely not Knightswood!
If you are living in Bearsden, north of Canniesburn Toll roundabout, and west of the Milngavie road which runs up past Asda, past Hillfoot station and onto Milngavie, you're in Bearsden Academy catchment.
Their associated Primary schools are: Castlehill, Baljaffray, Bearsden, Mosshead. Plus lots of kids from St Nicholas.
Other primaries in Bearsden - Colquhoun Park, Westerton, Killermont - feed into Boclair. Also a great school and they've just announced a new build.
What you need to understand is that your catchment applies for primary AND secondary. What has happened a lot in recent years is that parents have been able to get their child into a non-catchment school for primary as there is capacity. Then it comes to the end of P7, and they have to put in another placing request so their child can carry on with the rest of their friends. Every year it happens that kids don't get it, have to move to a different high school from all their friends.
Your starting point is knowing your catchment school.